Recently, Pope Francis declared that “the persecution of Christians today is even greater than in the first centuries of the church, and there are more Christian martyrs today than in that era.”

The slaughter of as many as 500,000 Christians in South Sudan since 2011 may not have received the attention it deserved. However, now the religious cleansing of Christians in Iraq resulting from Islamic jihadists’ conquest of lands Christians had called home since the first centuries A.D. cannot be ignored.

In a region where Christians and Muslims had previously lived in relative peace side by side for centuries, the past 10 years have witnessed some 1.1 million Christians being killed or driven from their homes. Since June, the fall of northern Iraq to the control of the Islamic State of Iraq and Syria (ISIS) has created more than a half-million refugees – both Christian and non-Christian.

The Islamic State blitzkrieg across northern Iraq has captured large caches of advanced weapons left by the United States for the Iraqi military. Tanks, armored vehicles, surface-to-air missile launchers, warehouses of machine guns and ammunition and even Black Hawk helicopters – captured in Samarra, Fallujah, Mosul and Tikrit – are in the hands of the Islamic State. Now the world’s most brutal terrorists have some of the most up-to-date military equipment available. In addition, the Islamic State has looted banks of some $500 million, seized five oil fields and Iraq’s largest electricity-generating dam – providing the means for self-funding the expansion of Islamic terrorist rule. Islamic State-controlled assets now generate $3 million in daily income and are valued at more than $2 billion – unprecedented in the annals of terrorism.

While the Hamas-Israel war has dominated the news recently, Islamic State terrorism against Iraqis – both Christian and non-Christian – this year has taken four times more innocent civilian lives than have been lost by the Palestinians in Gaza. Islamic State has now launched incursions into Lebanon and the Kurdish region of Iraq. Baghdad and Jordan are the next likely targets.

Jordan is a key U.S. ally, sharing borders with Israel, Syria, Iraq and Saudi Arabia. Islamic State terrorists have called for the execution of Jordan’s U.S.-backed King Abdullah II as an infidel and enemy of Islam.

Jordan’s precarious situation is further compromised by many young Jordanians who went to fight against Bashar Assad’s regime in Syria and are now returning more radicalized than before they left. In addition, Jordan, a country with a population of only 6.5 million, is burdened with more than 600,000 registered Syrian refugees now living within its border.

Islamic State has been using the conflict in Syria as a recruiting ground to enlarge its terrorist ranks, drawing on the 12,000 foreign fighters that have joined since the conflict started in 2011. The largest influx of foreign fighters have come from Arab states, and many have been so radicalized that they pose an internal terrorist threat – an Islamic State “fifth column” – within the countries to which they return.

However, there is a new and unprecedented threat with the Islamic State having recruited nearly 2,000 fighters with Western passports. Rep. Peter T. King, New York Republican and chairman of the House Homeland Security counterterrorism and intelligence subcommittee, has reported that among them are some 100 Americans who could be trained in terrorism and attempt returning to the United States as subversive Islamic State agents.

What are reasonable options to undertake and engage allies in the region to contain and defeat ISIS? For starters the United States should assist Turkey – a NATO ally that shares a border with Syria and Iraq. Turkish Prime Minister Recep Tayyip Erdogan’s options have been compromised by the ISIS capture of 80 Turkish hostages, including diplomats, last June in Mosul. With all the conflicting interests of his people, though, Mr. Erdogan knows the fall of Kurdistan to ISIS is unacceptable – creating a massive refugee disaster with likely destabilization of the Kurdish minority in Turkey. Self-interest compels Turkey to help Iraqi Kurds preserve their freedom and defeat ISIS.

The United States also needs to step up its dialogue, cooperation and planning with Arab allies that border Iraq – Jordan, Saudi Arabia and Kuwait. These three countries alone collectively possess formidable air power, consisting of more than 400 combat-ready F-15s, F-16s and F-18s.

There is no support for, nor is there need for, U.S. military boots on the ground, but there is no substitute for American advisers, intelligence experts, drones and counterterrorism special forces who can locate, identify and help take out high-value Islamic State targets and leaders in Iraq and Syria. Air power alone can’t win a war, but it can significantly diminish Islamic State forces. When used in coordination with ground forces, the odds of success are exponentially increased.

Over the past several months, the United States has deployed some 800 advisers, intelligence and special forces in Iraq presumably to lay the groundwork for operations against the Islamic State. The catalyst for commencing U.S. Air Force operations against the Islamic State finally came Thursday in what President Obama explained as a need to protect a humanitarian airlift to 40,000 of the Yazidi sect who fled to the safety of mile-high Mount Sinjar near Syria to avoid genocide at the hands of the Islamic State, and to protect American advisers and diplomats under Islamic State siege in Irbil, the Kurdish region’s largest city.

Mr. Obama’s authorization of limited and defensive use of air power against the Islamic State is not just too little, too late. The problem is, there’s no visible plan with moral clarity about the imperative of civilization prevailing over barbarism. What’s needed now is not prolonged indecision and half-measures, but real leadership that encourages allies to stand with us in winning hearts and minds about the value of life, and in sustaining a comprehensive strategy to defeat the Islamic State and related terrorist organizations.

Originally published in The Washington Times.